Generally, manholes to drain rainwater and sewage have pipe joining structures in which pipes 1, such as branch pipes, provided in a lower portion of the manhole, and drain pipes coupled to the branch pipes, are coupled to each other. Typically, pipe joints are used at junctions between the pipes 1, such as the branch pipes and the drain pipes of the manholes, to prevent water from leaking. The above-mentioned pipe joints can be adapted to join pipes 1 of various diameters.
A representative example of conventional pipe joints will be described herein below with reference to FIG. 1 showing its general construction. A conventional pipe joint includes a main body 2 which has at an inner surface thereof a cushion unit 5 made of rubber. The pipe joint further includes coupling parts 3 which have bent shapes and are coupled at both ends of the main body 2 by welding. The pipe joint further includes an extension part 4 which is provided on one end of the main body 2 while extending from the coupling part 3.
As shown in FIG. 2, the conventional pipe joint having the above-mentioned construction is mounted around a junction of pipes 1. In detail, the coupling parts 3 are coupled to each other by locking bolts 6 and locking nuts 7. The extension part 4 of the main body 2 is inserted between an end of the cushion unit 5 and the opposite end of the main body 2, thus being in close contact together into a stacked shape. By the above-mentioned coupling method, even though the pipes 1 have various diameters, the pipe joint can join the pipes 1 within a range capable of overlapping the extension part 4 and the opposite end of the main body 2.
However, in the case that two pipes 1, in which one pipe 1 is inserted into the other pipe 1, are joined using the conventional pipe joint, a gap undesirably occurs between an inner surface of the main body 2 of the pipe joint and an outer surface of the small pipe 1. In other words, because the main body 2 of the conventional pipe joint has a cylindrical shape having a constant diameter, although the cushion unit 5 provided inside the main body 2 has superior elasticity, it is very difficult to firmly seal the junction between the two pipes 1 coupled to each other to be stepped.
Furthermore, if the extension part 4 of the main body 2 is inserted too far between the opposite end of the main body 2 and the end of the cushion unit 5, a part of the cushion unit 5 may detach from the inner surface of the main body 2. Thus, the detached part of the cushion unit 5 may undesirably fold two or three times. In this case, gaps are caused in the detached part of the cushion unit 5. Water leakage may occur at such gaps.
In addition, because an area of a part of each coupling part 3, welded with the main body 2, is narrow, when the coupling parts 3 are coupled to each other by the locking bolts 6 and the locking nuts 7, the welded parts of the coupling parts 3 may break. Alternatively, the coupling parts 3 do not withstand the resistance of the main body 2 and, thereby, a gap between them may get wider.
[Disclosure]
[Technical Problem]
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a pipe joint which can be easily adapted to join pipes of various diameters, and in which even though a junction between the pipes is stepped, the junction is efficiently sealed, thus ensuring water tightness at the junction of the pipes.
Another object of the present invention is to provide a pipe joint in which a body part and coupling parts are configured as an integrated plate or the coupling parts are integrally coupled to the body part, thus providing superior durability, and increasing the productivity due to an improvement in a manufacturing process.